1. Field of the Invention
The present invention relates to a power supply apparatus, an electrical equipment, and an image forming apparatus. More specifically, the present invention relates to a power supply apparatus that supplies a plurality of electric powers with different voltages to the exterior, and an electrical equipment and an image forming apparatus that include the power supply apparatus.
2. Description of the Related Art
For example, an image forming apparatus, such as a printer, includes a processing unit that performs image processing and a driving unit that drives a photosensitive element and a polygon mirror in rotation.
The processing unit includes a central processing unit (CPU) and various electronic components that operate at 3 volts or 5 volts. On the other hand, the driving unit includes a motor that operates at a voltage (for example, 24 volts) higher than that for the electronic components. Therefore, an image forming apparatus includes a power supply apparatus that supplies a plurality of electric powers with different voltages.
When a short circuit occurs or when a large current flows in a circuit due to a load side failure or the like, abnormal heat may occur to increase failure, or in the worst case, smoking, ignition, or the like may occur.
For this reason, an overcurrent monitoring circuit is mounted on the power supply apparatus in order to stop the output when overcurrent flows.
For example, Japanese Patent Application Laid-open No. 2001-186760 discloses a power supply apparatus including: a detecting unit that detects the state of the apparatus and outputs the detection information; an abnormality judging unit that judges whether the detection information received from the detecting unit is abnormal based on a preset threshold and outputs an abnormal signal when judged as abnormality; and a breaking unit that breaks the input circuit of the apparatus based on the abnormal signal received from the abnormality judging unit. In the power supply apparatus, when the abnormality judging unit judges that the detection information is abnormal, the breaking unit immediately breaks the input circuit of the apparatus.
However, the power supply apparatus disclosed in Japanese Patent Application Laid-open No. 2001-186760 needs to mount a power supply for operating the abnormality judging unit, which inhibits downsizing and cost reduction.